C#

//getting size of picture box in sz1
public void ZoomIn()
        {
            //pictureBox1.SizeMode = PictureBoxSizeMode.StretchImage;
            if (sz1.Width >= 800 * 6)
                MessageBox.Show("Max ZoomIn");
            else
            {
                sz1.Width += 100;
                sz1.Height += 100;
                pictureBox1.Size = sz1;
                
                pictureBox1.Invalidate();
            }
            

        }

private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
            
                

                if (mybitmap == null)
                {
                    mybitmap = new Bitmap(pictureBox1.Image.Width, pictureBox1.Image.Height);
                    mybitmap.SetResolution(300, 300);
                }


                    rect = new Rectangle(e.X, e.Y, 0, 0);
                    pictureBox1.Invalidate();

           

        }




private void pictureBox1_Paint(object sender, PaintEventArgs e)
        {
            

                if (mybitmap == null)
                {
                    return;
                }

                
                    
                    using (Pen pen = new Pen(Color.Green, 2))
                    {
                       
                        
                            foreach (Rectangle r in rectangles)
                            {
                                e.Graphics.DrawRectangle(pen, r);

                                e.Graphics.DrawString(lab[c].ToString(), new Font(lab[c].ToString(), 8F), new SolidBrush(label1.ForeColor), r);
                                

                            }

                            
                    }
       
        }

/// <summary>
/// Returns a value indicating if the path contains the specified node type.
/// </summary>
/// <param name="nodeType">Specifies the node type.</param>
/// <returns></returns>
public bool Contains(BindingPathNodeType nodeType)
{
    return IndexOf(nodeType) != -1;
}

/// <summary>
/// Attempts to locate the first (zero-based) index position of the specified node type.
/// </summary>
/// <param name="nodeType">Specifies the node type.</param>
/// <returns></returns>
public int IndexOf(BindingPathNodeType nodeType)
{
    int intCount = parsedPathNodes.Length;
    for (int i = 0; i < intCount; i++)
        if (parsedPathNodes[i].NodeType == nodeType)
            return i;
    return -1;
}